Let’s be blunt: Microsoft stopped issuing security patches over four years ago. Using a fresh Windows 7 install on a modern network is like leaving your front door unlocked.
If you are a developer or IT professional with an active MSDN (now Visual Studio) subscription, you can legally access the original ISO files. This is the gold standard for purity. Windows 7 Ultimate 64 Bit Iso
Because Windows Update for Windows 7 is slow and partially broken, you need to manually install three specific updates before you can search for others. Let’s be blunt: Microsoft stopped issuing security patches